There are two kinds of cool moms: the velour-tracksuit-wearing, living-vicariously-through-their-children kind (see Amy Phoeler in "Mean Girls") and the slow-to-mature but still totally endearing kind (à la Lauren Graham in "Gilmore Girls").Needless to say, most would rather be raised by the latter. So we're happy to say that Megan Mullally, who Zap2it first reported would appear in "Happy Endings," will be channeling Lorelai Gilmore when she appears as Penny's (Casey Wilson) mom in episode 3 of the upcoming second season."Penny has the most positive mom of all time," creator and showrunner David Caspe tells Zap2it. "They're more like best friends than mother/daughter... so they're basically the 'Gilmore Girls.'"Mullally is a fan of "Happy Endings." And after running into Wilson at a party and expressing an interest in appearing on the show, producers put out the offer for her to play Penny's mother. "She's a very young mom," executive producer Jonathan Groff says of the 52-year-old...